It is unlikely that the countries that make up the European Union will ever federalize if every country has to decide to do it all at once. We have simply grown too large for that to be realistic, as shown by the failure of the Constitutional Treaty in the early 2000s and, more recently, by obstructionist behavior from some national governments.

A more realistic path is asynchronous federalization: countries federate when political and legal conditions align for them, and others join later.

Political moments in which some countries are open to federalization may occur sooner or later, but they are unlikely to occur everywhere at the same time. A window may open in one country and close again before it opens in another.

Federalization potential is not only political. It is legal too.

For some countries, joining a new sovereign European federation could require years of constitutional preparation. It might require not only a referendum on transferring additional sovereign powers, but also prior constitutional amendments to make that transfer legally possible in the first place. These requirements, and the time needed to work through them, vary by country.

For a European federation to emerge, preparation cannot wait for political conditions to align everywhere. Political windows can close as fast as they open. The playbook should already exist when the moment arrives.

This does not require predicting when or whether federalist politics will prevail in any given country. It simply means that if political conditions align, the legal and institutional groundwork is ready and can be acted on immediately.

I therefore propose two preparation tracks running in parallel, interacting throughout with a third political track that both enables them and is ultimately strengthened by them.

National Constitutional Roadmaps

The first preparation track is unglamorous but essential: understanding the constitutional and legal requirements in each country and translating them into concrete, country-specific plans for how that country could join a federation.

Some countries may need significant constitutional revision. Others may proceed mainly through treaty ratification. Some may be required, or may choose, to hold referenda. These pathways should be mapped in detail by national constitutional experts, working with federalist movements and parties, so that when a political window opens in a given country, execution can begin rather than design.

A European Constitutional Framework

The second preparation track is to develop a constitutional framework for the federation itself: what it would look like, how it would be governed, and how it would relate to the existing EU during a transition period when some countries have federated and others have not.

This work should begin within federalist movements and converge on a shared vision that can serve as an off-the-shelf starting point when a European Convention is eventually called.

Under the Treaty on European Union, a proposal for treaty amendment can be submitted by the European Parliament, a national government, or the European Commission to the Council, and the European Council can decide by simple majority to move the process forward. The full treaty-revision and ratification path would still apply, which is exactly why advance preparation matters.

The framework should specify the conditions under which the federation comes into being, for example a threshold combining a minimum number of member states with a population requirement, ensuring both member state representation and democratic legitimacy. It should also define institutional arrangements between a federal EU and the remaining legacy EU during transition, including clear accession pathways for countries that join later.

Eurofederalist Campaigns

Neither preparation track runs on its own. Triggering a convention requires political will. Commissioning and legitimizing national roadmaps requires political actors to champion them. This is where federalist movements and parties come in, not only as eventual campaigners for ratification in individual countries, but as the force behind the preparation itself.

What the preparation tracks give back to politics is something currently missing: something concrete to advocate for. Political arguments can center on the substance of the federal constitution, its relationship with the legacy EU, and the practical politics of transition, rather than on whether federation is conceivable at all.

Overcoming the barriers to federalization will require years of coordinated effort across Europe. But once national legal pathways are prepared and a constitutional framework is agreed, the decision facing each country becomes as simple as it can be: not “is this feasible?” or “what would it even look like?”, but simply, “do we join?”